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45. Effects of spherical Al2O3 grades on crack initiation of thermal conductive silicone pads under high-temperature aging.

Author

Wang, Tianlun, Qin, Wenbo, Shu, Dengfeng, Huang, Fei, Sun, Jiachen, Yue, Wen, and Wang, Chengbiao

Subjects
*ALUMINUM oxide, *POLYMER degradation, *SCANNING electron microscopes, *SILICONES, *CRACK propagation (Fracture mechanics)
Abstract

In this paper, the rule and mechanisms of crack initiation and propagation in the aging process of thermal conductive silicone pads (TCSP) were investigated by designing Al2O3 particle grading schemes with different particle sizes and mass ratios. Scanning electron microscope and energy dispersive spectrometer analysis showed that TCSP prepared with Al2O3 particles of various sizes according to the gradation ratio had the best anti-aging effect at high temperatures. At this time, the aging was mainly due to the aging degradation of the polymer matrix; When the proportion of small-size Al2O3 particles increases, aggregates and pore defects appear in TCSP. At this time, the main reason for its aging is that the high-temperature expansion of gas in pore defects accelerates the aging degradation of the polymer matrix; When the proportion of small-sized Al2O3 particles decreases, a large number of holes appear in TCSP and the coverage rate of the polymer matrix on Al2O3 particles decreases. The main reason for the high-temperature aging crack is that the gas between the holes expands at high temperature, resulting in the rapid extension of the crack and the polymer matrixes falling. [ABSTRACT FROM AUTHOR]

Published
2023
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46. Macroporous Perovskite-Structured LaFeO 3 Microspheres and Their Highly Sensitive and Selective Sensing Properties to Alcohols Gas.

Author

Qin, Wenbo, Yuan, Zhenyu, Shen, Yanbai, and Meng, Fanli

Subjects
*METAL oxide semiconductors, *MICROSPHERES, *GAS detectors, *ALCOHOL, *SURFACES (Technology), *ORGANOMETALLIC compounds, *METHANOL as fuel
Abstract

Alcohols detection is essential for the health of chemical and food production personnel. Metal oxide semiconductor (MOS) gas sensors are widely used, however, sensitive and selectivity of traditional MOS gas sensor is still a bottleneck issue. Recently, ABO3 perovskite-type MOS has attracted much attention due to its abundant and controllable physicochemical properties. In this article, macroporous perovskite-type LaFeO3 (LFO) microspheres were prepared by simple one step hydrothermal process. The gas sensing test results show that the LFO gas sensor is highly sensitive and selective to alcohols, especially methanol. For 100 ppm methanol, the response value can reach 120 at 215 °C. The excellent gas sensing properties are attributed to the macroporous characteristics (>100 nm), which facilitates the diffusion of methanol molecules inside the nanospheres, enhancing the contact between the gas molecules and the material and improving the gas sensing performance. In addition, the adsorption characteristics and electron exchange processes of eight gases on the material surface were investigated based on first principles analysis. The results show that the hydroxyl group is the main contributor to the stable adsorption of alcohols gas on the material surface. The perovskite-type LFO is a very promising sensitive material for alcohols detection. [ABSTRACT FROM AUTHOR]

Published
2023
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